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15x70 vs. 20x80 Obies for occasional non-mount use

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#1 Mike B

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Posted 29 June 2005 - 02:34 PM

I've decided to move on a binocular upgrade, and Oberwerk looks to be the logical choice for my situation. I've used a pair of inexpensive 70mm binocs hand-held for few-minute periods with an acceptable degree of comfort. Otherwise, have braced them on elbows on a comfy chair with arm-rests, or have a very decent (older) alum. tripod with a tilt-pan head, where the 70mm binocs on an "L" bracket were fairly stable & functional up to about 60* up-altitude.

My question is this- Are 20x80 Oberwerk Standards (listed at 4.5#) going to be a radically different proposition for brief hand-held viewing compared to their 15x70 (3.0#) brethren? And will i be seeing "deeper" for the added weight & cost, or will the optical gain be relatively insignificant for the efforts made?

Thank you all in advance for your experienced input. It would be proper to state that CN has enriched my Astronomy experience beyond what i could've imagined- i appreciate you all & this forum so very much!

regards,
:cool:mike b

#2 Guest_**DONOTDELETE**_*

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Posted 29 June 2005 - 03:20 PM

Mike,

I don't believe you will be able to hand hold the 20x80 standard for any length of time and do any useful viewing. These are long binoculars, and with most of the weight towards the end, I don't see it happening. However, you could have gorilla hands and strength and prove me wrong.

On a side note, I recently returned mine and ordered the 20x80 Deluxe II. The reason was biginoculars.com lists the 20x80 standard as having 3.5 degree FOV, but the binoculars actually have 3.2 stamped on the ocular housing. Helen at bigbinos said they would update the site to reflect the correct FOV. I thought I might as well go with the Deluxe II for $50 more and get a much shorter, waterproof, nitrogen purged bino with a nice hard case if the FOV is the same as the 20x80 Standard. Of course they weigh 7 lbs, so I don't think even a gorilla is going to hand hold them!

grace and peace,

Shawn B

#3 Joe Ogiba

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Posted 29 June 2005 - 03:29 PM

Mike, I have 20x60 Pentax PCF V's and I mount them all the time . I can't imagine using 20x80's handheld unless you rest your elbows on the arms of a bino chair and even then it would not be steady enough for me IMHO.

Joe

#4 Mike B

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Posted 29 June 2005 - 03:36 PM

"I don't believe you will be able to hand hold the 20x80 standard for any length of time and do any useful viewing..."
Hi Shawn-

Well-phrased answer! Particularly the "useful" comment... both the weight AND the magnification concerned me for a hand-held application.

Assuming, then, a mounted configuration, how say ye to the "depth" obtainable with the extra 10mm of aperture? I'd need to decide whether that gain would be worth losing the convenience of "gorilla" :lol: mode.

peace out,
mike b

#5 EdZ

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Posted 29 June 2005 - 03:44 PM

Hi Mike,

I would ditto the comments on "useful viewing".

As far as gain in what you see.
Given same quality 15x70 vs 20x80, which is what you are comparing here, you stand to see a fair amount of gain with the 80s. Not to much change in exit pupil, so the 80s will be nearly as bright. 30% more light gathering and 20x vs 15x will provide a pretty big gain in how deep a magnitude you can see. Small objects will be larger and better sized to see.

Go to the "best of" and look up the post on What you can see in different sizes binocs.

edz

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Posted 29 June 2005 - 03:54 PM

I would agree with Edz's post. 20x80s will see more dimmer objects and they will appear larger, but the difference between 10 to 15 mag was more noticeable to me than 15 to 20 mag IMHO.

I have a pair of Obie 15x70s and can hand hold them for a few minutes, but I use these mounted for extended sessions. They are great binocs with a wide FOV.

#7 Mike B

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Posted 29 June 2005 - 04:51 PM

Hi Ed-

Took your advice & swerved into the article "LM Binoculars"... very interseting! Since binocs are not typically "diffraction-limited" optics, nor are ever operating at optimal magnifications, the gain of those 10mm of aperture (70mm up to 80mm) is likely dwarfed by the gain of going from 15x to 20x. Yet any gains, to be seen & enjoyed at that level of magnification, will need a steady mounting to eliminate all motion.

If i'm understanding this correctly, those 20x80's would be fantastic mounted binocs- showing more, and fainter objects- better. But they're too much magnification to hand-hold... i'd be seein' as much in "gorilla" mode with the 15x70's, and probably enjoying the lighter weight & wider field. Plus, even the 70's will show more to their limits when mounted (as would any binocs!). Going to the 11x70's would possibly give a wee bit more handheld ease of viewing, but i'm not sure i wanna go backwards in optical reach with so much less mag... 15x70 looks like an optimal configuration.

I think i can see where i'm headed :watching:... thanks Ed & Shawn for the assuring voice of experience- tellin' me what i think i already suspected.
:cool:mike b

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Posted 29 June 2005 - 05:10 PM

I think they will be. Since you are considering only brief hand held use, I guess the difference in weight is not a factor. What will be a factor is the relatively large increase in magnification. That increase in magniifcation, I would think, would force you to have less of a tolerance for any motion. Any vibrations or jiggling on your part would counter the LM gains from the increased in magnification and objective area, let alone keeping the object pleasantly in your FOV.

I think you will definitely want to mount them.

#9 Mike B

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Posted 29 June 2005 - 05:58 PM

NW- The 15x70's i'd used before were used either mounted on a tripod or in my "bino" chair- a typical canvas camp chair with foot & arm rests, the armrests pulled way up high on the seatback to create elevated elbow supports. They weren't too bad just hand-held either, only for limited periods of time. As Joe O. stated above, 20x80's might be too much to be suitable even for a "bino-chair" & elbow application; I was really looking for more of a grab-'n-go set up, albeit the max such a set up could be. :cool: mike b

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Posted 30 June 2005 - 08:10 AM

Mounted 20x80 bins are not "grab-n-go"? :lol: Compared to my BT100, in my mind, a mounted 20x80 is definitely easily portable. As they say, "It's all relative.".

Have fun with your new bins regardless!

#11 Craig Simmons

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Posted 30 June 2005 - 09:06 AM

I find my 3.8 lb Stellarvue 15x63 (masked down from 70m) and either the 8 and 8 1/2 lb Stellarvue 20x85 and Oberwerk 20x90 respectively are very portable on a Bogen 3046. Initially I considered the heavier binos only short distance portable (out to the yard). I recently added a strap to the tripod which allows me to carry the weight on my shoulder and control the binos and Microstar head with one hand. I've been able to carry this 15-20 lb. package around the neighborhood very easily.

#12 Erik D

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Posted 30 June 2005 - 09:38 AM

My Burgess 20X80LW is ~3.6lbs. I use it for short periods without a mount while lying down an exercise mat and my head supported on a U shaped neck pillow. I grasp the 80mm bino very near the objectives. The wt of the bino are pressing straight down and resting lightly against my eye sockets.

Body built and arm strength has very little to to with steady holding of 4-5 lb weight. I weigh just over 150 lbs with slender arms but I don't find it difficult holding high power optics. Used to be a competive rifle shooter but have not been in competition for over 20 years. (I weighed 20 lb less and used 16-25X rifle scopes back then)

If you have experience holding 15X70s you MAY enjoy the 20X80 LW. I find 20X80s much more sastifying compared to my 12X50 and 12X60 binos. Prof Ed verified the 20X80 LW to have FOV ~3.7 deg!

Erik D

#13 Craig Simmons

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Posted 30 June 2005 - 09:59 AM

Erik, I've tried the lying down, grab the barrels method also. It works pretty good for semi-hand holdable binos, but like you said, not for long.

I think it's time to design and build a light saddle mount that straddles one's head and allows the binos to pivot in the needed directions. Add that to a cushioned turntable for comfort and foot steerage with an adjustable headrest and you have a very portable Bino Bed. I suspect this will lead to more sleeping than observing though.

#14 Mike B

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Posted 30 June 2005 - 12:40 PM

:funny:

#15 Mike B

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Posted 30 June 2005 - 12:51 PM

Simmons, eh... you don't design matresses, do you. :lol:

Actually, reminds me of the joke: "If all the people who slept during Church in the whole world were laid end-to-end...
they'd be a whole lot more comfortable."

Yeah- when i used 15x70's hand-held, i'd grip 'em up closer to the objectives, and that also while lying down- works very well, even for extended periods.

The LW 20x80 binocs i've looked at all seem to have shortish ER, & i really need as much of that as i can get using eyeglasses for my astigmatism. And it looks like Burgess is getting out of the large bino business... maybe BigBinoculars is taking over the world? Anybody else carry a ~$250 pair of 16x80 lightweights with 18-20mm of ER?

Thanks,
:cool:mike b

#16 Erik D

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Posted 30 June 2005 - 02:14 PM

mike b,

EdZ has done extensive testing to verify that inreasing X is more important than incremental increase of objective dia. I have performed several side by side test sessions of my 12X50 Roof prism Leupold vs my 12X60 Oberwerk. I can not detect improvement in limiting magnitude from my mag 4.5 backyard with the bigger pair.

The Orion Megaview is offered in 15X and 20X80 models but both are listed as having 3.5 deg FOV. Orion used to carry 16/20X 80mm models without the built-in tripod adapter. Again both had 3.5 deg FOV. I have the 20X80 model(2001). Given binos with the same FOV I would prefer the model with higher power.

My Buress 20X80 LW is listed as having 13mm ER but I think the actual eye relief is better. I do not need eye glasses to observe but I do have perscription glasses of -3.75 in the right eye. If I put on my glasses and fold the eye cups on my Burgess LW I CAN just see the full FOV. (I have regular glass lens, not the ultra-thin type) I feel more comfortable looking thru the Burgess LW than my Orion 20X80 with 15mm ER.

I believe the Oberwerk 20X80 LW is the same model as the Burgess LW( perhaps with better FMC coating on all surfaces). If you are sold on the idea of LW 20X80 binos with 70+ deg APFOV I think it's worthwhile giving the Oberwerk 80LW a try. I like my Burgess 20X80 LW so much I am thinking of getting a pair of Oberwerk 80mm LW while they are still available....

Erik D

PS. EdZ has the same Burgess 20X80 LW. Perhaps Ed can can verify the ER on his pair for you if he sees this post....

#17 SaberScorpX

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Posted 30 June 2005 - 02:29 PM

re: The LW 20x80 binocs i've looked at all seem to have shortish ER, & i really need as much of that as i can get using eyeglasses for my astigmatism.

Hi Mike-
Have you tried the Apogee 20x80LWs? $149 + free UPS here
Specs state a 3.8° FOV and 18mm of ER.

Saber

Ready to tackle the Herschel 400?
http://www.geocities...rpx/SGH400.html

#18 Mike B

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Posted 30 June 2005 - 02:31 PM

Erik-
Thanks very much for that info- very pertinent to my search! I was nearly ready to "pull the trigger" on the 15x70's with their 16mm ER, but will wait a bit 'til i fully pursue the ER & "gorilla"-mode usability of these 20x80 LW Obies. I don't mind folding down eyecups on my binos- have always had to do that if i wanted tight stars, but my concern was that with only 3.5* FOV, if i lost another 15% due to ER concerns, i'd be down to under 3* for FOV. But you've given me new hope! Maybe i'll poll Kevin at B.B. as well as Edz...
right arm!
:cool:mike b

#19 Mike B

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Posted 30 June 2005 - 02:44 PM

Woah, Nellie! I'm surprised i missed those !- being an Apogee customer- must be new... & they don't appear to be on their website. Will definitely check these out :grin:
Thanks Saber,
:cool:mike b

#20 EdZ

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Posted 30 June 2005 - 03:07 PM

Don't remember the ER on the Burgess 20x80LW. Can't find it written down in any of my notes. Moot point, it's no longer available.

The Obie 20x80 Standard has very long eye relief, but only 3.2° fov. Optically (LM, contrast, sharpness) far better than the Burgess LW. The binocular is 2-3" longer than a 15x70.

The newer Obie 20x80IF that NW has should show improvement over all the others mechanically and optically.

edz

#21 EdZ

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Posted 30 June 2005 - 03:22 PM

but the difference between 10 to 15 mag was more noticeable to me than 15 to 20 mag IMHO.



That is correct. The magnification gain from 10 to 15 is 50% greater than the magnification gain from 15 to 20. The jump from 10x to 15x can add about 0.5 mag LM. The jump from 15x to 20x will only add another 0.35mag.

Keep in mind these magnification jumps reduce exit pupil. While that will provide gain on 90% of all objects viewed, if you are a nebula (or comet) hunter, the diminished brightness due to smaller exit pupil might work against you. Magnification helps make tiny, high surface brightness objects more visible, but not very broad extended low surface brightness objects, such as the Merope nebula or the North America nebula.

edz

#22 Mike B

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Posted 30 June 2005 - 04:10 PM

Edz-
What, if anything, have you heard re: those Apogee 20x80's mentioned above?- the link is to "Optics Planet", where the posted picture looks identical to that on the "BigBinocs" webpage for their 20x80 LW Obies. They list as "~4 lbs", whereas the Obies are noted as 3.6 lbs... yet the Apogee's are noted as 3.8* & 18mm ER- the Obies list as 3.5* and 13mm ER. Hmmm...

In fact, i just noticed that "Optics Planet" also carries the 20x80 LW Obies, where the Obie's specs are correctly listed, per above. Intersetingly, here it is also stated that the Obies have the following:

"Low-reflection broadband multicoating is used on every air-to-glass surface, including prisms - an Oberwerk exclusive feature not found on any competitor's 20x80mm. Light loss due to reflection and scattering is minimized, providing the highest level of light transmission possible. New "slow-focus" provides precise focus control that won't drift."

While my head may be spinning a bit :confused: between these two contenders, with Erik's encouragement i'm looking seriously at the 80LW type binocs...

:help: Ed, if you, like Erik, can get the entire FOV in the LW Obies while wearing eyeglasses, that'll do'er for me- :grin:

While i like the sound of 18mm of ER, i'm perhaps more sold on the optical quality i hear coming out of the Oberwerk name. Just wanna be sure the ER will cut it for a typical eyeglass wearer!

Thanks for how you've helped me (and dare say hundreds) in the bino realm... and i certainly appreciate any light you can shed on the eyeglass-aspects of these 80LW Obies.
:cool:mike b

#23 Erik D

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Posted 30 June 2005 - 05:06 PM

mike b,

Just arrived home a little while ago. I double checked the ER of my Burgess LW with my glasses on. I CAN definitely see the full field with glasses on and the eye cups folded. Also checked usuable ER of my Orion 20X80s again. The Burgess LW is better.

I've seen many different Apogee big binos before but was not aware of a 80mm LW. A 20X80 LW with 3.8 deg FOV and 18 mm ER sounds VERY interesting....

Erik D

#24 Mike B

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Posted 30 June 2005 - 05:11 PM

Yeah, don't it though! I'm waiting for professor Z to get back in his office, to see what his take is...

just hope i get a passing grade this quarter :lol:
;)mike b

#25 EdZ

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Posted 01 July 2005 - 09:53 AM

I can't answer to the Obie 20x80LW. I've never used or seen a pair.

The Obie Standard is a much different binocular than thhe LW.

FWIW, I believe Kevin has written a letter to OpticsPlanet to stop using his advertising photos.

I don't know anything about the Apogee LW.

What we do know from past experiences is that some of these warehouses are selling old stock. I'm not sure there is any way to know if you are getting 1st generation of current genration.

edz


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